1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 *  Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
 4 *  Copyright 2003 Andi Kleen, SuSE Labs.
 5 *
 6 *  Modified for x86 32 bit architecture by
 7 *  Stefani Seibold <stefani@seibold.net>
 8 *  sponsored by Rohde & Schwarz GmbH & Co. KG Munich/Germany
 9 *
10 *  Thanks to hpa@transmeta.com for some useful hint.
11 *  Special thanks to Ingo Molnar for his early experience with
12 *  a different vsyscall implementation for Linux/IA32 and for the name.
13 *
14 */
15
16#include <linux/timekeeper_internal.h>
17#include <asm/vgtod.h>
18#include <asm/vvar.h>
19
20int vclocks_used __read_mostly;
21
22DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data);
23
24void update_vsyscall_tz(void)
25{
26	vsyscall_gtod_data.tz_minuteswest = sys_tz.tz_minuteswest;
27	vsyscall_gtod_data.tz_dsttime = sys_tz.tz_dsttime;
28}
29
30void update_vsyscall(struct timekeeper *tk)
31{
32	int vclock_mode = tk->tkr_mono.clock->archdata.vclock_mode;
33	struct vsyscall_gtod_data *vdata = &vsyscall_gtod_data;
34
35	/* Mark the new vclock used. */
36	BUILD_BUG_ON(VCLOCK_MAX >= 32);
37	WRITE_ONCE(vclocks_used, READ_ONCE(vclocks_used) | (1 << vclock_mode));
38
39	gtod_write_begin(vdata);
40
41	/* copy vsyscall data */
42	vdata->vclock_mode	= vclock_mode;
43	vdata->cycle_last	= tk->tkr_mono.cycle_last;
44	vdata->mask		= tk->tkr_mono.mask;
45	vdata->mult		= tk->tkr_mono.mult;
46	vdata->shift		= tk->tkr_mono.shift;
47
48	vdata->wall_time_sec		= tk->xtime_sec;
49	vdata->wall_time_snsec		= tk->tkr_mono.xtime_nsec;
50
51	vdata->monotonic_time_sec	= tk->xtime_sec
52					+ tk->wall_to_monotonic.tv_sec;
53	vdata->monotonic_time_snsec	= tk->tkr_mono.xtime_nsec
54					+ ((u64)tk->wall_to_monotonic.tv_nsec
55						<< tk->tkr_mono.shift);
56	while (vdata->monotonic_time_snsec >=
57					(((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
58		vdata->monotonic_time_snsec -=
59					((u64)NSEC_PER_SEC) << tk->tkr_mono.shift;
60		vdata->monotonic_time_sec++;
61	}
62
63	vdata->wall_time_coarse_sec	= tk->xtime_sec;
64	vdata->wall_time_coarse_nsec	= (long)(tk->tkr_mono.xtime_nsec >>
65						 tk->tkr_mono.shift);
66
67	vdata->monotonic_time_coarse_sec =
68		vdata->wall_time_coarse_sec + tk->wall_to_monotonic.tv_sec;
69	vdata->monotonic_time_coarse_nsec =
70		vdata->wall_time_coarse_nsec + tk->wall_to_monotonic.tv_nsec;
71
72	while (vdata->monotonic_time_coarse_nsec >= NSEC_PER_SEC) {
73		vdata->monotonic_time_coarse_nsec -= NSEC_PER_SEC;
74		vdata->monotonic_time_coarse_sec++;
75	}
76
77	gtod_write_end(vdata);
78}